The story of the 20th century cannot be told without the Soviet Union.  From the World War I to the Russian Revolutionn to WWII to the Cold War.  For the majority of this period, the Soviet Union (along with the United States) dominated World History.  The U.S.S.R. pops up all over the 20th Century.  So (since you're probably American), let's take a look at the "Evil Empire" and the role they played in the 20th Century.